Sarah Palin Levi Johnston is a LIAR -- We've NEVER Hidden Tripp

4/6/2012 5:00 AM PDT

Sarah Palin -- Levi Johnston is a LIAR ... We've NEVER Hidden Tripp

Mama Grizzly is clawing back at Levi Johnston ... claiming Bristol Palin's baby daddy straight up LIED when he claimed her family has been actively trying to block Levi from seeing his son, Tripp.

Sarah and Todd Palin have issued a statement to TMZ ... saying, "We have never hidden Tripp from Levi or discouraged Levi from spending time with him. Any suggestion that we have is false and contrary to our core beliefs."

The Palins add, "The last time either of us recall a conversation with Levi was in the summer of 2010 when Levi sat down at our house with us and personally apologized about lies he told to the media about our family. Neither of us have talked to him since that day."

The Palins are referring to the statements Levi made on "TMZ Live" this week ... when he accused the entire Palin clan of hatching a diabolical plan to keep him away from Tripp ... and said Sarah is the one pulling the strings.

But the Palins say Levi is full of moose droppings ... telling us, "We are disappointed that he continues to tell falsehoods about us to garner media attention. We encourage Levi and all non-custodial fathers to be fully engaged and to positively and fully participate in their children's lives. This includes not making misstatements about his child's grandparents."